Application of capillary electrophoresis to the drug analysis of forensic interest

Katarzyna Madej, Micha³ Wo¼niakiewicz

Abstract

Capillary electrophoresis (CE) belongs to the relatively new analytical techniques. This technique is characterized by high resolution potential, fast speed and small consumption of reagents. CE is used in forensic analysis of: protein and DNA fragments, explosive and gunshots, inks and drugs. Generally, analysis by CE consists in the separation of examined compounds in a capillary (20-100 µm ID) under high electric field (up to 30 kV). CE can work in a few separation modes which are modification of the basic one, i.e. capillary zone electrophoresis (CZE).

The most dynamic development of CE methods including drugs analysis, falls on past decade. A number of papers concerning CE determinations of narcotic drugs (e.g. amphetamines, heroine and opiates, cocaine, cannabinoids) and other drugs of forensic interest such as: barbiturates, benzodiazepines, tricyclic antidepressants and phenothiazines have been appeared. Usually, the above mentioned compounds were determined in seizured preparations, standard drug solutions and biological material such as: serum, plasma and urine.

In this work the possibility of the application of two CE modes: CZE and MECC (micellar electrokinetic capillary chromatography) to the analysis of phenothiazines and tricyclic antidepressants in the whole blood and pharmaceuticals have been investigated. The repeatability of migration times and detection limits of the examined drugs have been determined. The obtained results reveal that CE-CZE and CE-MECC are suitable methods for the separation and identification of the drugs tested in blood and pharmaceutical preparations as well. The drugs can be detected in blood samples at the low toxic concentrations.

For achieving legal defensibility, the forensic analysis results should be confirmed by at least two independent methods based on different physicochemical mechanisms with comparable sensitivity. From this point of view CE seems to be an alternative technique for commonly used analytical techniques in forensic toxicology such as GC and HPLC.